Here’s what fixed it for me.
I have had the Kickr for 6 weeks with absolutely no issues…loved every second on it. Then 3 days ago the symptoms described by you all in this thread started happening to me. I had changed nothing in my set-up to warrant this ugly behaviour…wild swings in power output despite a consistent 90rpm effort and complete losses of connection (0) watts. So I started reading all of the suggestions on how to fix it and here is what I found…
I decided to start making 1 change at a time and retest between changes.
Change 1 - I deleted and re-installing the Companion App on my phone …this did not fix it. Same symptoms when I tested.
Then I noticed that it was taking longer to connect to my Wahoo Heart Rate Monitor than normal. In fact it was looking for so long I cancelled and tried again. So I wondered…even though the HRM was only 4 weeks old could the battery be flat?
So I replace the battery in my HRM and voila the bluetooth connection was again back to immediate.
So I jumped back on the Kickr and tested again and bingo no more fluctuations in the watts.
So I can only assume that the poor HRM signal was somehow confusing the whole set-up or somehow interfering or maybe the App was continuously trying to reconnect and in doing so upsetting the connection to the Kickr as well. Who know s but my problem is gone.
So I’d suggest that you try replacing all your batteries (Cadence etc as well).